\pP Match P, named property. Use \p{Prop} for longer names.
\PP Match non-P
\X Match eXtended Unicode "combining character sequence",
- equivalent to C<(?:\PM\pM*)>
- \C Match a single C char (octet) even under utf8.
-
-A C<\w> matches a single alphanumeric character or C<_>, not a whole word.
-Use C<\w+> to match a string of Perl-identifier characters (which isn't
-the same as matching an English word). If C<use locale> is in effect, the
-list of alphabetic characters generated by C<\w> is taken from the
-current locale. See L<perllocale>. You may use C<\w>, C<\W>, C<\s>, C<\S>,
+ equivalent to (?:\PM\pM*)
+ \C Match a single C char (octet) even under Unicode.
+ NOTE: breaks up characters into their UTF-8 bytes,
+ so you may end up with malformed pieces of UTF-8.
+
+A C<\w> matches a single alphanumeric character (an alphabetic
+character, or a decimal digit) or C<_>, not a whole word. Use C<\w+>
+to match a string of Perl-identifier characters (which isn't the same
+as matching an English word). If C<use locale> is in effect, the list
+of alphabetic characters generated by C<\w> is taken from the current
+locale. See L<perllocale>. You may use C<\w>, C<\W>, C<\s>, C<\S>,
C<\d>, and C<\D> within character classes, but if you try to use them
-as endpoints of a range, that's not a range, the "-" is understood literally.
-See L<utf8> for details about C<\pP>, C<\PP>, and C<\X>.
+as endpoints of a range, that's not a range, the "-" is understood
+literally. If Unicode is in effect, C<\s> matches also "\x{85}",
+"\x{2028}, and "\x{2029}", see L<perlunicode> for more details about
+C<\pP>, C<\PP>, and C<\X>, and L<perluniintro> about Unicode in
+general.
The POSIX character class syntax
word \w [3]
xdigit
- [1] A GNU extension equivalent to C<[ \t]>, `all horizontal whitespace'.
- [2] Not I<exactly equivalent> to C<\s> since the C<[[:space:]]> includes
- also the (very rare) `vertical tabulator', "\ck", chr(11).
- [3] A Perl extension.
+=over
+
+=item [1]
+
+A GNU extension equivalent to C<[ \t]>, `all horizontal whitespace'.
+
+=item [2]
+
+Not exactly equivalent to C<\s> since the C<[[:space:]]> includes
+also the (very rare) `vertical tabulator', "\ck", chr(11).
+
+=item [3]
+
+A Perl extension, see above.
+
+=back
For example use C<[:upper:]> to match all the uppercase characters.
Note that the C<[]> are part of the C<[::]> construct, not part of the
matches zero, one, any alphabetic character, and the percentage sign.
-If the C<utf8> pragma is used, the following equivalences to Unicode
-\p{} constructs and equivalent backslash character classes (if available),
-will hold:
+The following equivalences to Unicode \p{} constructs and equivalent
+backslash character classes (if available), will hold:
+
+ [:...:] \p{...} backslash
alpha IsAlpha
alnum IsAlnum
You can negate the [::] character classes by prefixing the class name
with a '^'. This is a Perl extension. For example:
- POSIX trad. Perl utf8 Perl
+ POSIX traditional Unicode
[:^digit:] \D \P{IsDigit}
[:^space:] \S \P{IsSpace}
=item C<(?imsx-imsx)>
-One or more embedded pattern-match modifiers. This is particularly
-useful for dynamic patterns, such as those read in from a configuration
-file, read in as an argument, are specified in a table somewhere,
-etc. Consider the case that some of which want to be case sensitive
-and some do not. The case insensitive ones need to include merely
-C<(?i)> at the front of the pattern. For example:
+One or more embedded pattern-match modifiers, to be turned on (or
+turned off, if preceded by C<->) for the remainder of the pattern or
+the remainder of the enclosing pattern group (if any). This is
+particularly useful for dynamic patterns, such as those read in from a
+configuration file, read in as an argument, are specified in a table
+somewhere, etc. Consider the case that some of which want to be case
+sensitive and some do not. The case insensitive ones need to include
+merely C<(?i)> at the front of the pattern. For example:
$pattern = "foobar";
if ( /$pattern/i ) { }
$pattern = "(?i)foobar";
if ( /$pattern/ ) { }
-Letters after a C<-> turn those modifiers off. These modifiers are
-localized inside an enclosing group (if any). For example,
+These modifiers are restored at the end of the enclosing group. For example,
( (?i) blah ) \s+ \1
the time when used on a similar string with 1000000 C<a>s. Be aware,
however, that this pattern currently triggers a warning message under
the C<use warnings> pragma or B<-w> switch saying it
-C<"matches the null string many times">):
+C<"matches null string many times in regex">.
On simple groups, such as the pattern C<< (?> [^()]+ ) >>, a comparable
effect may be achieved by negative look-ahead, as in C<[^()]+ (?! [^()] )>.
got <d is under the >
Here's another example: let's say you'd like to match a number at the end
-of a string, and you also want to keep the preceding of part the match.
+of a string, and you also want to keep the preceding part of the match.
So you write this:
$_ = "I have 2 numbers: 53147";
This is grandfathered for the RHS of a substitute to avoid shocking the
B<sed> addicts, but it's a dirty habit to get into. That's because in
-PerlThink, the righthand side of a C<s///> is a double-quoted string. C<\1> in
+PerlThink, the righthand side of an C<s///> is a double-quoted string. C<\1> in
the usual double-quoted string means a control-A. The customary Unix
meaning of C<\1> is kludged in for C<s///>. However, if you get into the habit
of doing that, you get yourself into trouble if you then add an C</e>
projects / p5sagit/p5-mst-13.2.git / blobdiff